Yemen said on Sunday its security forces were still searching for two Finns and an Austrian whose whereabouts remain unknown since they were kidnapped in Sanaa.

Security services are "carrying out vast search and investigation operations to locate the kidnapped" foreigners, abducted on Friday in Sanaa, official news agency Saba quoted Interior Minister Abdelqader Qahtan as saying as he received an envoy from Finland.

Germany urged Egypt Sunday to get to the bottom of allegations of fraud leveled by the opposition after the adoption of a new, Islamist-backed constitution in a referendum.

"The reports from Egypt fill me with concern," Foreign Minister Guido Westerwelle said in a statement.

More than 60 civilians were killed on Sunday in a strike by Syrian regime warplanes on people queuing outside a bakery in the rebel-held town of Halfaya in the central province of Hama, a watchdog said, as regime warplanes pounded the capital's suburbs and the northern province of Aleppo.

The Syrian Observatory for Human Rights, which had earlier reported "dozens" killed, said the death toll could rise as at least 50 people had also been critically wounded.

Syria insisted on Sunday its military played no role in last week's deadly clashes between pro- and anti-regime forces inside the Yarmuk Palestinian refugee camp in southern Damascus.

Information Minister Omran al-Zohbi also called for all Palestinian refugee camps in Syria to be kept out of the country's 21-month conflict that a rights watchdog estimates has cost at least 44,000 lives.

The world's largest Muslim body on Sunday condemned threats made by Islamist rebels in Syria against two Christian towns, warning of fresh confessional strife in the war-torn country.

Such threats "are contrary to the precepts of Islam which calls for tolerance, brotherhood and peace," said the 57-member Organization of Islamic Cooperation based in the Saudi city of Jeddah.

Turkey has agreed to drop its ban on cooperating with Israel as a third-country NATO partner, a diplomat said Sunday.

Ankara cut off such cooperation after the Israeli army raided a Turkish ship carrying humanitarian aid to the blockaded Gaza Strip in 2010, leaving nine Turks dead.

U.N.-Arab League peace envoy Lakhdar Brahimi arrived in Syria on Sunday for talks on the country's crisis, Agence France Presse reported.

Brahimi entered Syria via a land border crossing with Lebanon after arriving earlier in the day at the Rafik Hariri International Airport from Cairo.

Egypt's opposition said on Sunday it will appeal a referendum seen as voting in a new constitution backed by ruling Islamists, and vowed to keep up a struggle that has spawned weeks of protests and instability.

Polling "fraud and violations" skewed the results of the two-stage referendum, the final leg of which was held on Saturday, the National Salvation Front charged.

Three separate bomb attacks killed a member of the Kurdish peshmerga security forces and three construction workers in Iraq on Sunday, officers and doctors said.

A bomb blast in an under-construction house in the town of Mishahada, north of Baghdad, killed the workers and wounded another, a police captain and a doctor said.

About 2,000 Iraqi protesters, demanding the ouster of Premier Nouri al-Maliki, blocked on Sunday a highway in western Iraq leading to Syria and Jordan, an AFP correspondent reported.

The protesters, including local officials, religious and tribal leaders, turned out in Ramadi, the capital of Sunni province of Anbar, to demonstrate against the arrest of nine guards of Finance Minister Rafa al-Essawi.